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RFID carrier sensing method and RFID system using this RFID carrier sensing method

  • US 8,531,271 B2
  • Filed: 07/27/2007
  • Issued: 09/10/2013
  • Est. Priority Date: 01/31/2005
  • Status: Expired due to Fees
First Claim
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1. An RFID system, comprising:

  • a reader/writer which has a controller section and a plurality of antennae each with characteristic polarization, and which sends a continuous carrier wave; and

    a tag which uses tag information to modulate the continuous carrier wave and sends back a response signal to the reader/writer, whereinthe controller section judges prior to send the continuous carrier wave, the level of the interference signal received from another reader/writer by switching each of the plurality of antennae for each of the plurality of channels and determines a channel and antenna for which the judged level of the interference signal is equal to or less than the threshold value, and receives a response signal from the tag by means of the determined antenna via the determined channel,wherein the channels are the respective bands of a frequency band that has been divided into a plurality of bandwidths.

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